---
title: replaceOrAppend
group: 'Array'
description: Replace item in array or append if no match
---

## Basic usage

Given an array of items, an item and an identity function, returns a new array with the item either replaced at the index of the existing item -- if it exists, else it is appended at the end.

```ts
import { replaceOrAppend } from 'radash'

const fish = [
  {
    name: 'Marlin',
    weight: 105
  },
  {
    name: 'Salmon',
    weight: 19
  },
  {
    name: 'Trout',
    weight: 13
  }
]

const salmon = {
  name: 'Salmon',
  weight: 22
}

const sockeye = {
  name: 'Sockeye',
  weight: 8
}

replaceOrAppend(fish, salmon, f => f.name === 'Salmon') // => [marlin, salmon (weight:22), trout]
replaceOrAppend(fish, sockeye, f => f.name === 'Sockeye') // => [marlin, salmon, trout, sockeye]
```
